There is two-stage process in the case of high-pressure production. In the first stage, microgranulate is obtained, which is then directed to the autoclave. In a reactor under high temperature discharge, the microgranulate softens and can be saturated with high-pressure gas. In this case, inert gases can be used. Expansion of the micropellet takes place during the emptying of the reactor, due to a sudden drop in pressure at the outlet. Lowering the temperature causes the granulate to solidify. Foamed granulate is dried and directed to storage silos.
Scheme of high-pressure pellet production.